This proposal involves a comprehensive investigation of the function of the G protein rod transducin in taste sensation. Transducin has a well- defined role in phototransduction where it acts to couple the membrane- bound rhodopsin to its effector molecule. Transducin recently has been identified in taste receptor cells and, although its function is not known, it is hypothesized to be involved in taste transduction. To determine the functional significance of transducin in taste transduction, transgenic mice will be developed in which the transducin gene will be "knocked out" or rendered nonfunctional by creating a deletion through homologous recombination. Mice deficient in the alpha subunit of transducin will be compared to wildtype siblings in terms of behavioral taste responses and peripheral neural processing of the taste system. The proposed research will determine if transducin has a direct role in taste transduction and what taste modalities are affected. Information derived from this proposal will aid in deciphering the fundamental biology underlying signal transduction and provide information regarding how events at the molecular level are transposed into quantitative neurophysiological and behavioral phenomena.